Electrical apparatus



c. l. Mc NEIL 2,038,186

ELECTRICAL APPARATUS A ril 21, 1936.

Filed Sept. 2, 1933 mymy I '1/171/1/z 191111111114 wllallzzl %gllllllin i 1 E l INVENTOR Char/es M /Vef/ ATTORN Patented A t. 21, 1936 UNITED STATES PATENT OFFICE Eclipse Aviation Corporation,

East Orange,

N. J., a corporation of New Jersey Application September 2, 1933, Serial No. 688,039

1' Claim,

This invention relates to voltage regulators for dynamo electric machines, and particularly for generators driven from engines of variable speed, and operating to supply a variable or constant current demand.

An object of the invention is to provide in a regulating system including a rheostat, novel means for actuating the rheostat to vary the strength of the generator field immediately upon the occurrence of a rise or fall in line voltage,

and then hold the new setting steadily, and without the period of fluctuation which characterizes certain conventional regulators now used.

In the preferred embodiment, shown schematically in the accompanying drawing, the rheostat is operated by difierential gearing driven in one direction or the other, as required, by electro-magnetic means, the movement in either direction being stopped instantly, as soon asthe normal voltage is restored. It is to be understood, however, that the maintenance of the electrical connections precisely as shown is not essential, the drawing being illustrative rather than definitive of the scope of the invention.

In the drawing,

Fig. 1 is a diagrammatical view of the invention as applied to the variable speed generator;

Fig. 2 is a view in elevation showing the rheostat actuating mechanism; and

Fig. 3 is another view of the rheostat actuating mechanism as seen at right angles to the view point of Fig. 2.

In the drawing, reference character G designates agenerator armature rotatable through suitable mechanical connections (not shown) leading to an internal combustion engine crank-shaft or other prime'mover. The shunt field winding 6 of the generator is shown as connected in series with the coil 1 of a rheostat, the movable arm 8 of which is electrically connected to one brush 9 of the generator, through interposed leads I l and I2. The arm 8 is also shown as mechanically secured to a rock-shaft l3 which terminates in a cage carrying a pair of bevel gears I4 and I5 (Fig. 2) constituting elements of a. difl'erential planetary gear set which includes additional bevel gears l6 and I1, the latter two being in constant mesh with the other two and mounted for rotation on separate, but aligned, shafts l8 and I9 respectively, the said shafts being capable of independent step by step rotation in response to electrical impulses created by the means now to be described. By way of example the difierential gear set is shown as of the type disclosed in Patent N0. 1,619,552 granted to Charles Waseige on March 1st, 1927; the specific construction used is not claimed except generically, as an element of the combination comprising the regulating system.

The means for actuating a selected one of the 5 shafts I8, [9, while preventing actuation of the one not selected, preferably includes a pair of electro-magnets having windings 2| and 22, respectively, surrounding cores whose ends cooperate with armatures 23 and 24, respectively, to 10 cause relatively rapid oscillation thereof as current is passed through the associated winding at regularly recurring intervals of relatively high frequency. In order to transmit these oscillations to the shaft l8 or the shaft l9 (depending 15 upon which electro-magnet is energized) the former is provided with a ratchet wheel 21 rotatable step by step in a clockwise direction, as viewed from the left in Fig. 2, and the latter with a similar ratchet wheel 28 rotatable step by step 20 in a clockwise direction, the rotation in one case being produced by means of a pawl 3| pivotally connected to one end of the armature 23, and the other armature 24 being provided with a similar pawl 32 having engagement with the 25 teeth of ratchet 28.

The means for selecting the proper electromagnet for energization is shown in Fig. 1 as constituted by a third electro-magnet 33 having an armature 34 adapted to occupy any one of three 30 positions, depending upon the strength of the magnetic attraction thereupon, which in turn depends upon the voltage impressed upon the winding 33, said voltage being the generator voltage by reason of the fact that the winding 33 is 35 connected directly across the line, as by leads 3'! and 38. When the voltage-is sub-normal, the armature engages fixed contact 39; when abnormal, it engages fixed contact 40; and when normal, it remains between said contact, but out of 40 engagement therewith; a suitable centering spring 4| or other means being provided to prevent movement of the armature so long as the deviation from normal remains negligible. A second spring 45 is provided to draw the armature 45 downward under sub-normal voltage conditions. Lead 42 connects contact 33 with electro-magnet 2|, and lead 43 connects contact 40 with electromagnet 22. Both magnets 2| and 22 have a common connection 44 with the terminal 48 of a com- 50 mutator or circuit interrupter 41, the other terminal of which connects with the positive side of the main generator line, as shown at 48. This device 41 is driven through suitable reduction mechanism (not shown) from the generator 55 shaft 40, and includes a disk having a non-conducting portion ll adapted to interrupt the flow of current once each revolution; hence the frequency of energization of the windings ll, 22 will be governed by the speed of this circuit interrupting commutator 41. Preferably this speed will be approximately one-fourth that of generator armature.

From the foregoing operation is as follows:

Upon an increase in voltage the coil 38 overcomes spring and causes armature 34 to engage contact 40 to energize coil 22 in the circuit including conductors l8 and H. Each time this circuit is broken at 41, pawl 82 and ratchet 28 operate through diflerential ii to move arm 8 so as to decrease the flow of current through field 8 by increasing resistance 1 in series with field B. If the voltage decreases below the predetermined normal value contacts 38, solenoid 2| and ratchet mechanism ll, 21 operate through gears Iii and ll to increase the voltage. i

Upon starting the generator. the entire field resistance may be cut out of circuit by providing itis apparent that the a shunt switch 52 which opens erator reaches approximately of the desired voltage, the switch being opened by means of a solenoid I connected across the line. The baiancing, or centering spring ll serves not only as a deterrent to excessive vibration of the armature 34, but also as a means of compensating for the variable magnetic pull upon the armature as-the air gap between armature and core increases and decreases.

What is claimed is:

In combination with a rheostat having a mov able resistance varying element, means for moving said element comprising an actuating shaft, reciprocable means responsive to a voltage drop for rotating said shaft in one direction, additional reciprocable means responsive to a voltage rise for rotating said shaft in the reverse direction, and a diflerential gear train connecting said reciprocable means with said actuating shaft, said gear train having one element thereof locked against rotation by one of said reciprocabie means while the remaining elements of the gear train are being rotated.

CHARLES I. McNEIL.

when the gen- 

